[lldb-dev] ASLR disabled by default - thoughts?

[Todd Fiala]

> You can disable it on Linux at the kernel level, but that's not how we
want to use it in this scenario.

Meaning it can be done system-wide, but that's not how we plan to use it on
Linux.


On Fri, Aug 15, 2014 at 9:49 AM, Todd Fiala <tfiala at google.com> wrote:

> > Is ASLR per-launch / per-process on other platforms?
>
> Linux allows you to set it per process, and based on previous comments,
> MacOSX does as well (there's a posix_spawn flag for it on that platform).
>  You can disable it on Linux at the kernel level, but that's not how we
> want to use it in this scenario.
>
> You don't have a way to disable it just for a process on Windows?
>
> -Todd
>
>
> On Fri, Aug 15, 2014 at 9:33 AM, Greg Clayton <gclayton at apple.com> wrote:
>
>> Yes it should be disabled by default for all systems. It is this was on
>> MacOSX by default. The linux plug-in will need to be fixed.
>>
>> > On Aug 14, 2014, at 9:41 AM, Todd Fiala <todd.fiala at gmail.com> wrote:
>> >
>> > [I'm not seeing this show up in the archives two hours after I posted
>> it from my google account, so I'm sending it from my gmail account.  Pardon
>> if this shows up again in the next 24 hours from my @google.com
>> account...]
>> >
>> > ---------- Forwarded message ----------
>> > From: Todd Fiala <tfiala at google.com>
>> > Date: Thu, Aug 14, 2014 at 7:29 AM
>> > Subject: ASLR disabled by default - thoughts?
>> > To: "lldb-dev at cs.uiuc.edu" <lldb-dev at cs.uiuc.edu>
>> >
>> >
>> > Hey all,
>> >
>> > Regarding this bug:
>> > http://llvm.org/bugs/show_bug.cgi?id=20658
>> >
>> > We've been discussing the idea of having ASLR disabled by default when
>> launching processes within lldb.  Currently it looks like the default
>> behavior is to have it enabled, and require explicitly disabling to get
>> that behavior for the process.
>> >
>> > It seems like it might make more sense to have it disabled by default -
>> that way code references would likely be static across debugger runs, which
>> seems to be more what we want when tracking down issues across code runs.
>> >
>> > Any thoughts on this?
>> >
>> > The counterargument I could make for changing it would be (aside from
>> legacy compatibility issues perhaps on the MacOSX/iOS side) - taking the
>> exe out of its native state on the OS.  If a bug is ASLR sensitive, the
>> user might miss it.  And so behavior in the debugger could differ from the
>> exe in its native state.  Not sure how relevant that is for the majority of
>> usages, though.
>> >
>> > I'll be fixing the fact that Linux is ignoring this altogether.  But
>> while I'm in there, I could flip the default if we wanted to do it.  If not
>> globally, we'd probably pursue defaulting it on Linux (and Ed seems to like
>> it for FreeBSD as well, so maybe for not Apple in that case?)
>> > --
>> > Todd Fiala |   Software Engineer |     tfiala at google.com |
>> 650-943-3180
>> > --
>> > -Todd
>> > _______________________________________________
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>> > lldb-dev at cs.uiuc.edu
>> > http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
>>
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>
>
>
> --
> Todd Fiala | Software Engineer |  tfiala at google.com |  650-943-3180
>



-- 
Todd Fiala | Software Engineer | tfiala at google.com | 650-943-3180
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